Seems like there are two issues being addressed by the idea of making ammo storages auto-load:
- Differentiate bullets from power.
- Make ammo storage more useful.
i think these are both laudable goals, though I don't think they necessarily need to have the same solution.
Having some sort of auto-load and/or auto-transport mechanism (conveyor belts?) for bullets could make them a pretty interestingly different, though it begs the question why can't you do the same with power.
My original idea for differentiating ammo (and I may still do this, at least in singleplayer) was that ammo would cost money and/or resources to produce and have a much lower production rate than power. Thus, you'd need ammo storages to cache a supply of bullets because producing them during battle would take too long unless you had an huge number of factories. But I think to make that balanced, the capacity of ammo storages (and presumably missile storages as well) would have to be greatly increased. The only reason I haven't done that already (which I think should happen regardless of whether factory production rate is reduced) is that then I would need to change how bullets are visually represented in the storage since there's not enough room (or video memory) to show every single bullet.
So my current plan is to put off increasing ammo storage capacity until mining gets added, at which point I'm planning to turn ammo/missile storage (but probably not power storage) into generic storage rooms that can store pretty much anything from bullets & missiles to mined resources to FTL fuel (except probably not power).